1. Field of the Invention
The invention relates to a blood pressure monitoring system in fields requiring continuous blood pressure monitoring of a patient in an operating room, an intensive care unit, a first-aid room, an extracorporeal dialysis room, and the like. More particularly, the invention is directed to a blood pressure monitoring system utilizing pulse wave propagation time.
2. Related Art
To monitor the blood pressure of a subject by continuously measuring his or her blood pressure, the following methods have heretofore been available. An oscillometric, noninvasive method is designed to measure blood pressure by wrapping a cuff to the upper part of an arm of the subject. A direct, invasive method is designed to measure blood pressure by puncturing an artery of the subject.
By the way, the noninvasive blood pressure measuring method using the cuff may, in some cases, overlook a drastic change in blood pressure due to a shock when the measuring cycle in fixed time measurement is long (e.g., when the measuring cycle is set to 5 minutes or more).
If the measuring cycle is reduced to, e.g., 1 minute to overcome this problem, the blood vessel around which the cuff is wrapped is burdened, which in turn imposes the problem of causing internal hemorrhage.
Further, in the case of fixed time measurement, frequently applied cuff wrapping force that is more than necessary burdens the patient, and therefore causes somnipathy and the like.
On the other hand, the direct, invasive blood pressure measurement not only gives the subject a mental burden due to invasion or brings about the problem of infection, but also gives too much work to the medical staff by involving more labor than in noninvasive blood pressure measurement.